Long-term monitoring reveals unprecedented stability of a vent mussel assemblage on the Mid-Atlantic Ridge

•This paper presents the longest daily time-series of plurisdisciplinary data within a vent assemblage.•The diffuse-flow habitat was highly stable over 7 years  with small-scale variability mainly related to tidal periodicity and localised temperature anomalies.•The Bathymodiolus azoricus mussel assemblage and zoanthid patches were remarkably stable.•Microbial mats displayed heterogeneous spatio-temporal dynamics.•Our results question the assumption that vent assemblages are ephemeral and highly dynamics.